Encapsulated additives

ABSTRACT

A process for treating a substrate, being a fabric or leather, where an homogenous mixture of particles based on a maleimide polymer comprising a thermo-regulator additive is applied to a substrate and subsequently dried on it.

TECHNICAL DOMAIN OF THE INVENTION

The field of the present invention relates to the incorporation offunctional additives, such as thermo-regulators, in sub-micron particlesbased on a maleimide polymer, and to the uses thereof on differentsurface types, such as in fabrics.

BACKGROUND OF THE INVENTION

Fabrics (woven, knits, non-woven, . . . ) are an intersection ofdifferent yarns, fibers and tapes. Paper, wood, carton are also based onintersected fibers (e.g. cellulosic). The functionality of intersectedfibers can be adapted by additives, such as encapsulated additives.

The encapsulation of additives is well known in the textile industry andhas been specifically developed there. For instance,melamine-formaldehyde encapsulated thermo-regulators, anti-microbial orflame retardants have been developed for improving the textileproperties in textile industry. Almost all the encapsulation systems arebased on melamine formaldehyde chemistry, at least for thethermo-regulator additives, allowing to encapsulate high amounts offunctional additives, such as thermo-regulators.

Indeed, the encapsulation of high amounts of the functional additives isusually necessary to meet commercially-acceptable standards. Forinstance, in the case of thermo-regulators additives (e.g. a specificwax) for special textiles, the current market standard is set at 1000J/m², and values of 2500 J/m² are those of a top heat absorber. Thusthere is a need to stably add high quantities of functional additives.

However, several disadvantages occur, such as the difficulties to applyhigh quantities of the functional additive, or detrimental consequencesfor the end-product, including increased rigidity or impaired colors,requiring further correcting additives. Moreover, depending on thefunctional additive to incorporate, different chemistries must becombined resulting into unstable formulations. Furthermore,melamine-formaldehyde based formulations must be quite viscous,otherwise, there is sedimentation.

In other words, to meet customer's standards, high amount of particlesmust be added, which is challenging. On the other hand, any blending ofadditives results into diluted additives and any dilution of oneadditive is detrimental since requiring addition of more particles.Thus, when thermo-regulators are applied on textile, usually no otherfunctional additives can be added on the same surface, unless based ondifferent chemistries.

Moreover, the durability of the currently marketed additives is notsufficient. Even in the case of additive incorporation inside the targetstructure, additives might diffuse over the time.

Processing conditions furthermore limit the possibility to choiceadditives to encapsulate, for instance, heat-unstable additives cannotbe used for capsules having a production process requiring hightemperatures (smoke release, problems with volatile components, . . . ).

WO 2008/014903 discloses an aqueous polymer dispersion made by reactinga co-polymer of maleic anhydride and styrene with an aqueous solution ofammonia for performing an imidation reaction. This polymer has then beenused as replacement of melamin-formaldehyde for encapsulation of oils orparaffin so as to impart a hydrophobic effect to paper. However, thisstudy has not addressed the challenges of textile industry, such as theneed to load high amounts of functional additives.

SUMMARY OF THE INVENTION

The present invention relates to a process for treating a substratecomprising the steps of forming particles based on a maleimidecontaining polymer comprising a functional additive so as to form ahomogenous mixture, this homogenous mixture being applied to thesubstrate and being dried or cured.

Advantageously, to the homogenous mixture of maleimide-based particlescomprising a functional additive, a polymer formulation (the polymerhaving a Tg between −60° C. and 50° C., more preferably between −55° C.and 0° C.) is added forming a second homogenous mixture, so that thepolymer formulation once dried or cured forms a film on the substrate,wherein the maleimide-based particles are dispersed. Preferably, themass ratio between the maleimide-based particles and the polymer addedwith the formulation is comprised between 1:100 and 100:1, preferably,between 1:10 and 10:1, more preferably between 1:3 and 3:1.

Preferred polymers having a Tg between −60° C. and 50° C. are selectedfrom the group consisting of acrylics, polyurethanes, poly vinylacetate, Polyamides (PA), styrenebutadiene latex, natural or syntheticrubber, poly vinyl butyral, polyethylene, Ethylene Vinyl Acetate (EVA),polyesters, natural latex, bio-based polymers (e.g. polymers andderivatives thereof from monomers from natural sources, such aspoly-neoprenes, poly-isoprenes and polylactic acid), and halogenatederivatives thereof. Preferably, the maleimide-based particle (furthercomprising functional additives) is a reaction product of a co-polymerof maleic anhydride and styrene with an alkyl amine. Preferably at least50% of the anhydride is transformed into the imide (e.g. between 50% and95%, possibly between 60% and 90% or even between 60% and 80%).

Advantageously, the maleimide-based particle comprises one or,preferably several, functional additive(s) (embedded in the sameparticles or embedded in different particles) selected from the groupconsisting of thermo-regulating agent (e.g. a specific wax), flameretardant, anti-microbial agent, insecticide, antimite anti-acaridagent, aroma or odorant, UV or IR adsorbing agent, plasticizer andrigidity-affecting agent, preferably these particles comprise athermo-regulating agent and possibly further comprise another functionaladditive of the above list.

Preferably, the thermo-regulating agent is a component or a mixture ofcomponents having a solid-liquid transition phase between 4° C. and 50°C., more preferably, the transition phase temperature (from 80% solid to80% liquid) of the thermal regulating agent is narrow (e.g. in a rangeof less than 10° C., preferably, less than 4° C.). Suitablethermo-regulating agents are selected from the group consisting ofalkanes, paraffin, wax, mineral oils, vegetable oils or fats andmodified (i.e. hydrogenated or fractionated) vegetables oils.

Preferably, the maleimide-based particle comprises between 10 wt % and70 wt % of the functional additive(s): wt of the sum of the functionaladditive:total wt of the maleimide-based particles.

Preferred substrates are selected from the group consisting of fabrics(e.g. textiles, non-woven fabrics; any textile or fabrics are suitable),cellulosic material (paper, carton boards), leather (natural orartificial), wood, paints and concrete. A most preferred substrate is asurface, such as fabrics (a textile or a non-woven fabric; for instancewovens, knits, tufted, stitch bound, carpets, . . . ) or syntheticleather.

A fiber (cellulosic or to be used in fabrics) is also a possiblesurface.

Preferred polymer formulations are selected from the group consisting ofa solution, an emulsion, a dispersion or a solvent-free composition(e.g. of monomers and/or of oligomers), more preferably, the polymer isin the aqueous phase.

Preferably, the mixture added on the substrate (preferably furthercomprising the polymer formulation) is dried, for instance upon heating,or cured, for instance upon UV exposure.

The mixture is added to the surface by spraying, coating, printing,laminating or by impregnation (i.e. dipping so as to incorporate a knownamount of the mixture). The coating step is preferably made by theapplication of a foam (instable, stable or crushed), or by kiss roll.Low viscous to very high viscous pastes can be applied by thistechnique.

A related aspect of the present invention is the substrate coated afterthis process.

Another related aspect of the invention is a (a homogenous) compositioncomprising particles based on a maleimide polymer further comprising athermo-regulating agent (e.g. a specific wax) and possibly one orseveral other functional additive.

Preferably this formulation comprises, further to the maleimideparticles, a formulation of a polymer having a Tg between −60° C. and100° C. (preferably between −55° and 50°, more preferably between −50°C. and 0° C.).

Preferably, the maleimide polymer comprises a poly(styrene maleimide)polymer.

The weight ratio between the particle and the polymer added to thiscomposition together with the formulation is advantageously comprisedbetween 1:100 and 100:1, preferably, between 1:10 and 10:1, morepreferably between 1:3 and 3:1.

Preferably, the maleimide-based particle (further comprising functionaladditives) is a reaction product of a co-polymer of maleic anhydride andstyrene with ammonia or an alkyl amine. Preferably at least 50% of theanhydride is transformed into the imide (e.g. between 50% and 95%,possibly between 60% and 90% or even between 60% and 80%).

This (homogenous) composition can be in the form of a foam or of apaste: a paste or a foam comprising, consisting essentially of, orconsisting of this composition.

Another related aspect of the invention is the use of a (a homogenous)composition comprising particles based on a maleimide polymer forencapsulating at least two additives selected from the group consistingof thermo-regulating agent (e.g. a specific wax), flame retardant,anti-microbial agent, aroma or odorant, UV or IR adsorbing agent, andrigidity-affecting agent.

Preferably, in this use, the composition further comprises a formulationof a polymer having a Tg between −60° C. and 100° C. (preferably between−55° and 50°, more preferably between −50° C. and 0° C.)

Preferably, in this use, the maleimide polymer comprises a poly(styrenemaleimide) polymer.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1: Diagram showing the measurement of glass transition temperature(Tg) of a polymer of the present invention.

FIG. 2 shows the heat absorption properties of different compositions ofthe present invention.

FIG. 3 shows the absorption properties in function of heating/coolingcycles.

FIG. 4: Dispersion of poly(styrene maleimide)-based particles.

FIG. 5: Dispersion of poly(styrene maleimide)-based particles:polymeraccording to a preferred aspect of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The inventors have found that it is possible to use the small particlesbased on a maleimide polymer to encapsulate functional additives in anamount sufficient to allow the additive to exert its desired function,even in the case of the additive, or of one of the additives, is athermo-regulating agent.

The addition of a polymer formulation (of a Tg between −60° C. and 100°C., preferably between −55° and 50°, more preferably between −50° C. and0° C.) to the maleimide-based composition, despite of the dilutiveeffect caused by the polymer, that can be major, allows to more stablyincorporate the maleimide particle on a substrate such as a surface andis even useful to narrow the temperature transition range to the desiredtemperature (e.g. corresponding to the temperature of the skin).

Furthermore, the smooth process conditions associated to polymaleimide-based particles allow to work in one single step with severaladditives.

In addition, the choice of the polymer formulation allows to easilyadapting the stiffness of the resulting composition, while theadaptation of its relative abundance with regard to the maleimide-basedparticle allows the optimization of the resulting properties.

Finally, the present mixture, which is stable and non-viscous, can beapplied in different forms, such as a foam or a paste, that will in turnproduce specific properties (e.g. breathability when applied as a foamvs air tight when applied as a paste), depending on the needs.

The inventors have chosen the challenging way to try to develop, for thetextile industry, particles based on a poly(styrene maleimide) particlesand not to select the well-established melamine-formaldehyde coatingsystem. Indeed, a suspension of poly(styrene maleimide) particles, whendried, results into a gel full of cracks, then into a powder. This makesit challenging to use such particles as an encapsulating system to bestably applied on substrates such as surfaces, especially in textiles(exposed to weather conditions, to friction, to washings, . . . ), atleast if the goal is to have a long-lasting effect.

A first aspect of the present invention is a process for treating asubstrate comprising the steps of forming particles based on a maleimidecontaining polymer and comprising a functional additive, of obtaining anhomogenous mixture, of adding this mixture on a substrate, and ofallowing the mixture to dry or to cure. Advantageously, the processfurther comprises a step of mixing a polymer formulation to theparticles based on a maleimide containing polymer and comprising afunctional additive so as to form a second homogenous mixture; in thisprocess, the drying or curing step allows the polymer to become a filmon this substrate, for instance a film where the polymer forms a matrixwhere the maleimide containing particles are homogenously dispersed.

Advantageously, the maleimide containing particles are small, with amean diameter between (about) 100 nm (preferably about 200 nm) and(about) 1 μm (preferably less than 300 nm).

By “particles based on maleimide” or “particles based on a maleimidepolymer”, it is preferably meant a poly(styrene maleimide) copolymerstably charged with a functional additive.

The “particles based on maleimide (or on a maleimide polymer)” may alsobe formed from other cyclic anhydride (for instance an unsaturatedorganic molecule with two carboxylic groups on one molecule, so as toform a cyclic anhydride, possibly with a molecular weight of less than300 Da, possibly less than 200 Da). These cyclic anhydrides areco-polymerised with olefins such as styrene, ethylene, propylene,alpha-olefins. The cyclic anhydride is usually maleic anhydride, but canalso be itaconic anhydride or substituted derivatives of maleicanhydride. The corresponding cyclic anhydride containing polymers(co-polymer) are then reacted with an alkyl amine to form thecorresponding reaction products: imides, amides and ammonium salts.Preferably, the cyclic anhydride is for more than 50% transformed intothe imide (e.g. between 50% and 95%, possibly between 60% and 90% oreven between 60% and 80%). After the transformation the maleimidecontaining polymer will form a particle. During the transformation ofthe cyclic anhydride into the maleimide containing polymer non-watersoluble or slightly water soluble products can be added. These productswill be encapsulated during the transformation process. The resultantparticles have usually a size smaller than 1 micrometer, mostly evensmaller than 300 nm. The encapsulated additive can make up till 70% ofthe total weight of the combination encapsulant and encapsulatedproduct.

Due to its small size the maleimide coating particles have multipleadvantages compared to the melamine formaldehyde encapsulating systems.The small size provides a much higher stability in the aqueous phase,while having the possibility to keep the viscosity low. The maleimidecontaining particles are more homogeneously embedded in a resultingcoating. Especially in thin coating layers the particles will not stickout of the coating surface.

When combined with polymeric binders the maleimide containing particleswill more act as inert materials compared to melamine formaldehyderesins, meaning that the physical properties of the polymeric binderswill more prevail. As such when adding low Tg polymeric binders thesoftness of the binder will be sensed better in combination with themaleimide containing particles than with melamine formaldehyde resins.

Such maleimide containing particles, especially the particles based onthe poly(styrene maleimide) copolymer can behave as a sponge. Theadditive is stably incorporated (able to stay there for more than 1month, preferably more than 2 months, even more preferably more than 1year) in the matrix. The addition of the polymer formulation isbeneficial for this aspect.

By “functional additive”, it is meant any product that is able toprovide a desired property and/or functionality to the target substrate.Possible additives are selected from the group consisting ofthermo-regulators (e.g. a specific wax), flame retardant, (other)hydrophobic compounds, biocides (anti-microbial such as antifungal orantibacterial, insecticide such as antimite, anti-mosquito, anti-acarid)light absorbing and/or emitting compounds, odorant, odor controllingagent, skin care agent, color pigment and probiotic material.

Advantageously, several functional additives can be applied in one stepof the process of the present invention, either because they areincorporated in one maleimide-based particle, or if severalmaleimide-based particles, comprising different functional additives,are mixed.

Indeed the inventors have found that the maleimide-based particle iscompatible with a lot of functional additives and, on the contrary todifferent coating systems, the mixing of differently loadedmaleimide-based particles is not challenging from a chemical point ofview (except for the dilutive effect that is solved thanks to thepossibility offered by the present invention to apply very high amountsof particles).

The glass transition of a polymer (Tg) is the temperature at which themorphology of the polymer changes from a hard and relatively brittlestate into a rubber like state. The Tg can preferably be measured bydifferential scanning calorimetry where the material is heated at a rateof 10K/min and the heat capacity is recorded in function of thetemperature. In other words, the Tg can be measured by plotting the heatcapacity as a function of temperature, then the Tg temperature isderived from the intersection of two tangents (at the start of theendotherm and at the maximal variation).

The Tg temperature can then be defined as the middle (B) of the onset(A) and the end (C) of the increase in heat capacity (FIG. 1).

Alternatively, the Tg temperature of a polymer is fixed at a viscosityof 10¹² Pa·s.

The polymer (or a mixture of polymer) usually have a Tg between −60° C.and 100° C. (preferably between −55° and 50°, more preferably between−50° C. and 0° C.). The lowest Tg values being associated to softeningeffects, the highest Tg values being associated to a stiffening.

Mixtures of polymers (without taking into account the particles based onmaleimide polymers) can be used in the polymer formulation, providedthat the resulting Tg value (without taking into account the particlesbased on maleimide polymers) remains in the range as above.

The Tg value of the poly(styrene maleimide)-based particle is muchhigher, in the range of 180° C., which allows process conditions atrelatively high temperatures, provided that the functionalities of theadditive(s) are preserved.

Preferred polymers are selected from the group consisting of acrylics,polyurethanes, poly vinyl acetate, Polyamides (PA), styrenebutadienelatex, natural or synthetic rubber, poly vinyl butyral, polyethylene,Ethylene Vinyl Acetate (EVA), polyesters, natural latex, bio-basedpolymers (e.g. polymers and derivatives thereof from monomers fromnatural sources, such as poly-neoprenes, poly-isoprenes and polylacticacid), and halogenate derivatives thereof.

The mass ratio between the particle based on maleimide, comprising atleast one functional additive, and the polymer present within theformulation can conveniently be fixed at about 1:1 (i.e. the mass of themaleimide polymer+the mass of the other coatings+the mass of the atleast one additive(s)=about the mass of the added polymer). However,this ratio can vary. It is preferably not below 1:100 and not higherthan 100:1. Usual ratios are comprised between 1:10 and 10:1, preferablybetween 1:5 and 5:1, more preferably between 1:3 and 3:1 or close to1:1. The ratio may be varied according to the needs; the importantaspects is to avoid a too heavy dilution of the functional additive(thus not too low ratios, yet ratios below 1:1 have been found asacceptable, even in the case of incorporation of thermo-regulators onfabrics) and to allow the resulting mixture to still form a filmcomprising the particles (thus not too high).

Preferably, the formulation of the polymer is a solution or adispersion, such as an aqueous dispersion of a polymer.

However, depending on the process, the polymer formulation can be amixture comprising one or several monomers and/or oligomers (forinstance to be polymerized at the curing step), and this mixture can besolvent-free. Alternatively, the polymer formulation can be an emulsionor dispersion, which is advantageous if foams are to be produced.

The drying step is chosen according to the standard practice. Drying isusually performed by heating. In this case, if a polymer formulation ispresent, the temperature should be fixed at a temperature higher thanthe Tg of the polymer (the Tg of the polymer molecule present in thepolymer formulation) and lower than 220° C., preferably lower than 180°C. (the Tg of the particles). An usual temperature in the textileindustry is of about 120° C. Relatively higher temperatures ranging from180° C. to 220° C. can be fixed for heating steps not longer than 30seconds. Heating can also be performed by irradiation (e.g. microwave,IR). The drying step can also be done at room temperature.

When monomers and/or oligomers are present in the formulation, thepolymerization is performed in situ, and, for instance, the heatingstep/curing step is achieved upon UV-irradiation.

In any case, care should be taken to select drying or curing conditionsthat do not detrimentally affect the particle's additives, such as toohigh temperatures for a too long time period or too heavy irradiation.In other words, the incorporation of heat- or radiation-sensitiveadditives will reduce the options but, in view of the wide flexibilityallowed by the present invention, there is room to select the mostadapted drying/curing conditions depending on the additive(s) present.

Specific processes according to the present invention are thus:

A process for treating a substrate (fabrics) where a formulation of apolymer is added to a poly(styrene maleimide)-based composition so as toobtain a homogenous mixture, this mixture being added to the substrateand being dried (preferably by heating), wherein the formulation of thepolymer is a solution, a dispersion or an emulsion, preferably anaqueous solution, an aqueous dispersion or an emulsion comprising anaqueous phase.

Another related process is a process for treating a substrate (fabrics)where a formulation of a polymer is added to a poly(styrenemaleimide)-composition so as to obtain a homogenous mixture, thismixture being added to the substrate and being cured (preferably upon UVexposure), wherein the formulation of the polymer consists of one orseveral monomers and/or of oligomers that will subsequently undergopolymerization. Possibly the formulation of the polymer is solvent-free.

A related aspect of the present invention is the substrate (fabrics)coated when carrying this process.

In other words, the present invention further relates to substratefurther comprising a film of a polymer comprising a (an homogenous)dispersion of particles of a poly(styrene maleimide)-compositioncomprising at least one additive(s).

Among them is a knit impregnated with a mixture of poly(styrenemaleimide)-based particles (Ps) comprising a thermo-regulator andfurther the polymer composition made of polyurethanes (PU) and anelastomer (El) (for instance in a weight ratio of Ps:PU:El 3:0.5:0.5).This composition is transparent, and the resulting knit keeps itssoftness and elastic properties, together with a high cool effect level.

Other options is to impregnate a knit with a mixture of poly(styrenemaleimide)-based particles comprising a phase change material, such as athermo-regulator (Ps/Tr) and poly(styrene maleimide)-based particlescomprising a flame-retardant (Ps/Fr) and further comprising the polymercomposition made of acrylic polymer (PA) (Ps/Tr:Ps/Fr:PA 3:2:1). Thiscomposition is transparent, and the resulting knit is flame-resistant,wash durable and keeps its elastic properties, in addition to have the“cool touch” effect.

Other options is to impregnate a knit with a mixture of poly(styrenemaleimide)-based particles comprising a wax and poly(styrenemaleimide)-based particles comprising a flame-retardant and furthercomprising the polymer composition made of polyurethanes and anelastomer (for instance in a weight ratio of Ps/Tr:Ps/Fr:PU:El3:1:0.5:0.5).

Alternatively, an instable foam made of poly(styrene maleimide)-basedparticles comprising thermo-regulators:acrylic polymer (Tg=−50° C.) canbe applied to a woven by back coating (weight ratio Ps:acrylic 3:1), ora stable foam in weight ratio Ps:acrylic 1:1 can be applied by backcoating. The resulting woven remains breathable and soft and hasacquired an intense “cool touch”.

Beside impregnation of fibers, the mixture of the present invention(e.g. made of poly(styrene maleimide)-based particles:polyurethane; 1:1)can be sprayed on the top surface of a foam, such as PU/latex foam, thenallowed to dry at ambient temperature. The resulting foam is soft,elastic and easily applicable.

Another related composition is made of poly(styrene maleimide)-basedparticles further comprising one functional additive (for instance athermo-regulator additive) and a polyol that is liquid atroom-temperature. This composition further comprises a blowing agent(that can be water) and a cross-linking agent (e.g. isocyanate). Thiscomposition is then cured to form a foam where the additive is embedded.

Another related aspect of the present invention is a paste or,preferably, a foam comprising (or consisting (essentially) of) thecomposition of the present invention.

EXAMPLES Example 1 Encapsulation of a Functional Additive

The inventors have used the aqueous dispersion as in WO 2008/014903,further comprising thermo-regulators (octadecane). After drying, thiscomposition became a hard surface (FIG. 4) risking to turn into a powderunder friction. The inventors have measured the heat absorptionproperties of this composition (FIG. 2, lines).

Example 2 Coating According to the Invention and Suitable for TextileApplications

The inventors then mixed a composition comprising thermo-regulators(octadecane) as in the comparative example with an aqueous compositionof an acrylic polymer with a Tg of −50° C. so as to obtain an homogenousmixture. The inventors firstly selected a 1:1 ratio (driedpowder:polymer).

The inventors then dried the homogenous mixture upon heating at 120° C.for 2 min (i.e. a rapid evaporation). The inventors obtained a film withgood technical properties where the poly(styrene maleimide) coat ishomogeneously dispersed. Then the inventors have measured the heatabsorption in function of the temperature.

Due to the dilution, the total heat absorption was reduced (FIG. 2).

However, the peak of maximal absorption was sharper, meaning that theefficacy of heat absorption at the target temperature (thus thefunctionality) is almost kept despite the dilutive effect.

Moreover, as shown in FIG. 3, the absorption values remain constantafter heating/cooling cycles.

By varying the nature or the relative amount of the polymer, theinventors have been able to displace the position of the peak, thusallowing flexibility to optimize the coating, depending on the end useof the substrate. Eg, stretchable fabrics, tight fabrics, soft fabrics,stiff fabrics, . . . .

Example 3 Application of the Coating According to the Invention in aBreathable Textile

The inventors then mixed the polymer composition as in Example 2 (in a1:1 mass ratio) so as to obtain an homogenous mixture in the form of afoam.

Then the inventors have applied the foam to a textile at a highconcentration on the back side of the substrate by foam applicationtechnique before the drying step as in Example 2.

The inventors have noticed that the coating allows the air to passthrough. As such, it is difficult to generate foams from melamineformaldehyde-based compositions. The maleimide-based capsules allow theinsertion into an easy applicable coating formulation and to maintainnice foaming properties, which secures air permeability of the treatedsurface. Furthermore, at these very high concentrations, the color onthe face of the substrate has not been affected and the “cool touch”effect is boosted by applying the encapsulated wax on one side of thefabric, meaning that the heat absorption capacity of the textile isbetter than in melamine-formaldehyde based compositions. Thisapplication remained stable on the textile for the time considered.

Example 4 Wash-Durable Flame Retardant

The inventors have used the aqueous dispersion as in WO 2008/014903,further comprising a flame retardant and then mixed it with an aqueouscomposition of a polymer with low Tg ranges of −50 to −10° C. (such asacrylic- or polyurethane-based polymers) so as to obtain an homogenousmixture in the form of a solution. Then the inventors have applied thesolution to a textile by impregnating it at a high concentration inorder to meet the specific flame retardant standards before the dryingstep as in Example 2.

The inventors have noticed that the coating allows two features: a verygood flame retardant effect due to the possibility to load much higherconcentrations than melamin-formaldehyde alternative, even with takinginto account the dilution due to the addition of the polymer, and thedevelopment of a wash-durable barrier due to the coating itself.Interestingly, the coating is wash durable and resistant to weatherconditions.

Example 5 Application of Particles Containing Two Additives

The inventors have then encapsulated a thermal regulating wax inpoly(styrene maleimide) particles, as well as flame retardant additivesin poly(styrene maleimide) particles. These two types of particles havebeen mixed together with a polymer formulation (PU:elastomer; 1:1) andthe mixture has then been applied on a textile substrate (e.g. a knit)by impregnation, and the substrate has been dried. The overallproperties of the substrate, including breathability, transparency,softness, elasticity, comfort, color and design have been kept.Moreover, the two functionalities have been stably incorporated to theknit.

1. A process for treating a substrate comprising the steps of: formingparticles based on a maleimide polymer comprising a functional additiveso as to obtain a homogenous mixture of the particles, applying saidmixture to the said substrate, drying or curing said mixture on saidsubstrate so that said particles are fixed on said substrate, whereinsaid functional additive is a thermo-regulator and said substrate is afabric or leather.
 2. The process of claim 1, wherein the maleimidepolymer comprises poly(styrene maleimide).
 3. The process of claim 1wherein size of the particles is lower than 1 μm.
 4. The processaccording to claim 1, wherein the particles comprise a further additiveselected from the group consisting of flame retardant, anotherhydrophobic compound, biocide, light absorbing and/or emittingcompounds, odorant, odor controlling agent, skin care agent, colorpigment and probiotic material, and wherein the thermo-regulator has anarrow transition phase temperature.
 5. The process according to claim1, wherein, before application on the substrate, the homogenous mixtureof the particles is mixed with a polymer formulation to form a secondhomogenous mixture, the polymer present within said formulation having aglass transition temperature (Tg) between −60° C. and 100° C., in a massratio between said particles and said polymer comprised between 1:10 and10:1 (w_(particle):w_(polymer)), wherein a Tg value of said polymer ismeasured by plotting heat capacity as a function of temperature, andsubsequent derivation of said Tg from an intersection of two tangents.6. The process of claim 5, wherein the polymer having a Tg between −60°C. and 100° C. is selected from the group consisting of acrylics,polyurethanes, poly vinyl acetate, polyamides, styrenebutadiene latex,natural or synthetic rubber, poly vinyl butyral, polyethylene, EthyleneVinyl Acetate, polyesters, natural latex, bio-based polymers, andhalogenate derivatives thereof.
 7. The process according to claim 5,wherein the mixture or the second mixture is applied on the substrate byspraying, coating, printing, lamination or impregnation.
 8. The processaccording to claim 5, wherein the mixture or the second mixture added onthe substrate is dried upon heating.
 9. The process according to claim5, wherein the second mixture added on the substrate is cured uponUV-irradiation.
 10. A substrate obtainable by the process according toclaim
 5. 11. A composition comprising particles based on a maleimidepolymer, said particles comprising a thermo-regulator additive.
 12. Thecomposition of claim 11, wherein the thermo-regulator additive has anarrow transition phase temperature.
 13. The composition of claim 11,wherein the particles further comprise another additive selected fromthe group consisting of flame retardant, another hydrophobic compound,biocides, light absorbing and/or emitting compounds, odorant, odorcontrolling agent, skin care agent, color pigment and probioticmaterial.
 14. The composition according to claim 11, wherein themaleimide polymer comprises poly(styrene maleimide).
 15. The compositionaccording to claim 11, wherein size of the particles is lower than 1 μm.16. The composition according to claim 11 further comprising aformulation of a polymer having a Tg between −60° C. and 100° C.,wherein a mass ratio between the particles and the polymer present insaid formulation is comprised between 1:10 and 10:1, wherein the Tgvalue of said polymer is measured by plotting heat capacity as afunction of temperature, and subsequent derivation of the said Tg froman intersection of two tangents.
 17. A foam or a paste consistingessentially of the composition according to claim
 11. 18. A method forencapsulating at least two additives on a substrate, the methodcomprising: forming particles based on a maleimide polymer comprising athermo-regulator additive and a second additive selected from the groupconsisting of flame retardant, other hydrophobic compounds, biocides,light absorbing and/or emitting compounds, odorant, odor controllingagent, skin care agent, color pigment and probiotic material so as toobtain a homogenous mixture of the particles, applying said mixture tosaid substrate, and drying or curing said mixture on said substrate sothat said particles are fixed on said substrate, wherein said substrateis a fabric or leather.
 19. The method of claim 18, wherein thethermo-regulator additive has a narrow transition phase temperature. 20.The method of claim 18, wherein the maleimide polymer comprisespoly(styrene maleimide).
 21. The method according to claim 18, whereinthe homogenous mixture further comprises a formulation of polymer havinga Tg between −60° C. and 100° C. and wherein the mass ratio between theparticles and the polymer present within said formulation is comprisedbetween 1:10 and 10:1.